Thermoplastic Polyolefin-Based Slush Powder Compositions

ABSTRACT

A thermoplastic polyolefin (TPO) powder is provided. The TPO powder includes an olefin-block copolymer (OBC), polypropylene copolymer, an adhesion promoter, a sulfur-free stabilizer additive, a composition including a non-migratory hindered amine light stabilizers (HALS) and a color pigment, and talc. A TPO material formed from the TPO powder and methods of making the TPO powder and TPO material are also provided.

BACKGROUND AND SUMMARY

The present disclosure relates generally to polyolefin-basedcompositions for slush-molding shells, such as for automotive interiorskins, that adhere to polyurethane-based foams during foam-in-placeprocesses.

Traditionally, soft skins used in automotive interiors, such as forinstrument panels, door uppers, consoles, and the like, are made using aslush-molding process. Many skins are back-foamed by a foam-in-placeprocess, which is a process through which, for example, polyurethanefoam is injected and/or formed between a skin and a hard substrate,resulting in desired haptics or a desired sense of touch and feel.

Slush molding involves heating a mold (typically a 3-4 mm thick nickelmold), pouring a polymeric powder or resin into the heated mold, androtating the mold. While the mold is rotating, at least a portion of thepowder melts and forms to an interior surface of the mold having adesired shape. After cooling and removal from the mold, a skin havingthe desired shape is formed. During this process, it is important thatthe powder or resin flows smoothly within the mold. Polyvinyl chloride(PVC) resin, for example, has an amorphous nature that exhibits goodflowability for slush molding. In contrast, traditional thermoplasticolefin formulations have hooks and tails resulting from pulverizationtechniques that lead to an unacceptably poor flowability for slushmolding, which in turn leads to higher scrap rates and inferiorproducts.

Foam-in-place processing is used for automotive interiors to achievedesired haptics. Foam-in-place processing involves injecting anisocyanate and a polyol between an outer skin (e.g., made by slushmolding) and a rigid support (e.g., a plastic support for an instrumentpanel) to form a polyurethane foam that bonds the skin and the rigidsupport together. The resulting product has very soft haptics, due atleast in part to the polyurethane foam. The polar nature of PVC andthermoplastic polyurethane (TPU) makes them excellent skin candidatesfor achieving a desired adhesion between the skin and the polyurethanefoam, whereas non-polar thermoplastic polyolefin (TPO) has poor adhesionand requires an additional surface treatment in order to adequatelyadhere to polyurethane foam. However, the effectiveness of surfacetreatments, such as flame treatment and plasma treatment, are limited bythe design of the component being fabricated. Therefore, PVC and TPU arewidely used in the automotive industry for slush-molded parts and softskins, and TPO is not.

PVC is an excellent candidate for slush molding due to cost benefits andthe reasons provided above. However, its performance depends on aplasticizer, which can deteriorate over time and at varioustemperatures, and develops a less than desired pliability attemperatures below about −30° C. TPU can overcome these issues, but iscost prohibitive for many automotive applications. Another common issuewith PVC and TPU is that they both release volatile organic compounds(VOCs), which are regulated in many countries through legislation.

U.S. Pat. No. 6,812,285 describes a thermoplastic elastomer (TPE)composition for slush molding. The TPE composition is apolypropylene-hydrogenated block copolymer having (a) at least onepolymer block A with a primary component that is a vinyl aromatichydrocarbon monomer unit and (b) at least one polymer block B with aprimary component that is a hydrogenated butadiene monomer unit.

U.S. Patent Publication No. 2012/0070665 describes a thermofusible TPEcomposition for slush molding. The formulation includes 40-70 wt. % of aselectively-hydrogenated styrenic block copolymer (HSBC), and 1-30 wt. %of a butylene homopolymer, a butylene copolymer, or a combinationthereof. This formulation is cryogenically milled to obtain slushpowder.

U.S. Pat. No. 8,674,027 describes a TPO elastomer composition in powderform, including an olefin-block copolymer (OBC), a linear ethylenepolymer, and/or a linear ethylene polymer, and a propylene polymer blendfor slush molding of skins, such as for interior applications, includinginstrument panels.

Despite references describing TPE or TPO for slush molding products, PVCand TPU continue to be used in many commercial applications in theautomotive industry. Reasons for this continued use of PVC and TPUinclude (i) uneven flow behavior of TPE/TPO powders resulting fromcryogenic or room temperature grinding, which yields slush moldingproducts with uneven thicknesses and high scrap rates; (ii) pooradhesion of TPE/TPO with polyurethane foams with and without surfacetreatments, such as flame treatments, corona treatments, and plasmatreatments; (iii) many TPE/TPO products do not meet aging requirementsat 120° C.; (iv) scratch resistance is lost over time with TPE/TPOproducts; and (v) difficulty of airbag deployment through TPE/TPO panelswithout having large breaks (unacceptable failure mode).

Slush-molding grade TPO powder with excellent polyurethane adhesion,scuff and mar, low fog, UV resistance, subzero temperature performance,and acceptable airbag deployment is desired. TPO is considered for thispurpose because of its low VOC output, lack of plasticizer content, andrecyclability.

In various aspects of the current technology, a TPO composition isprovided as TPO pellets or as a TPO powder (formed from the TPOpellets). The TPO pellets are configured to be processed into artificialleather skins or rolled films. The TPO powder is configured to be slushmolded into a shaped TPO material having the benefits of PVC and TPU,but also having a low VOC output, good adhesion, long-term high heatperformance, and reliable air bag deployment (for instrument panelapplications).

The TPO composition includes an OBC, polypropylene copolymer, and amaleic anhydride-grafted OBC. In certain aspects, the OBC isethylene-1-octene copolymer and the maleic anhydride-grafted OBC isethylene-1-octene copolymer grafted with maleic anhydride. In someaspects, the TPO material also includes an antimicrobial agent, such asgraphene and optionally a metal oxide.

The TPO powder has an angle of repose of greater than or equal to about26° to less than or equal to about 34° and a bulk density of greaterthan or equal to about 18 lb/ft³ to less than or equal to about 21lb/ft³. The TPO powder has spherical particles and is suitable forslush-molding processes for making a TPO material, such as, for example,automotive interior skins for doors and instrument panels having athickness of greater than or equal to about 0.8 mm to less than or equalto about 1.4 mm. The TPO material directly bonds to open cell foams withan adhesion peel strength of greater than or equal to about 3 N/inwithout being subjected to secondary processing, such as flametreatments. Therefore, the TPO material is disposable over an open cellfoam disposed on a rigid substrate so that a resulting article includesthe open cell foam disposed between the TPO material and the rigidsubstrate, wherein the TPO bonds directly to the open cell foam.

In various other aspects of the current technology, a method of makingthe TPO powder includes combining an OBC, polypropylene, and an adhesionpromoter to form a mixture; melt extruding the mixture to form anextruded material; pelletizing the extruded material to form TPOpellets; and grinding the TPO pellets to form the TPO powder. The TPOpowder is slush-molding grade.

In various other aspects of the current technology, a method offabricating an article includes introducing the TPO powder to aninterior of a mold, wherein the mold has an interior surface having apredetermined shape; heating the mold to at least partially melt the TPOpowder; during the heating, rotating the mold to coat the interiorsurface with the at least partially melted TPO powder; and cooling themold to form a molded article having the predetermined shape. In someaspects, the article is an automotive vehicle component, such as aninstrument panel, an A-pillar, a B-pillar, a C-pillar, a steering wheelskin, an airbag cover, a door trim panel, a door handle, a pillarhandle, a roof handle, a center console, a knee bolster, a seatmechanism cover, or a sun visor.

Additional features and advantages can be ascertained from the followingdescription and appended claims taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an interior trim panel including aTPO material in accordance with various aspects of the currenttechnology.

FIG. 2 is a cross-sectional view, taken along line 2-2 of FIG. 1,showing the interior trim panel.

FIG. 3 is a perspective view showing an article including a TPO materialin accordance with various aspects of the current technology.

FIG. 4 is a perspective view showing a first antimicrobial TPO materialin accordance with various aspects of the current technology.

FIG. 5 is a perspective view showing a second antimicrobial TPO materialin accordance with various aspects of the current technology.

FIG. 6 is a perspective view showing a third antimicrobial TPO materialin accordance with various aspects of the current technology.

FIG. 7 is a perspective view showing an antimicrobial TPO materialdisposed on at least one sublayer in accordance with various aspects ofthe current technology.

FIG. 8 is a diagrammatic flow chart showing a method for making a TPOpowder in accordance with various aspects of the current technology.

FIG. 9 is a diagrammatic flow chart showing a method for fabricating anarticle composed of a TPO material in accordance with various aspects ofthe current technology.

DETAILED DESCRIPTION

The TPO composition of the current technology is configured to preparearticles by slush molding, film casting, and thermoforming, such thatthe articles comprise a TPO material derived from the TPO composition.The TPO composition can be in the form of pellets or a powder. Thearticles are, for example, interior components of an automotive vehicle,such as an instrument panel, an A-pillar, a B-pillar, a C-pillar, asteering wheel skin, an airbag cover, a door trim panel, a door handle,a pillar handle, a roof handle, a center console, a knee bolster, a seatmechanism cover, a sun visor, and the like.

An interior trim panel for a wheeled automotive land vehicle is shown inFIGS. 1 and 2. The interior trim panel is preferably an instrument panel10, but may alternately include a center console 12, a separate airbagcover, a door trim panel, a knee bolster, a seat mechanism cover, apillar cover, or the like. A steering wheel 29 is also shown in FIG. 1.The instrument panel 10 includes an outer skin 14, a middle pliable foamlayer 16, and an inner rigid substrate 18. The steering wheel 29 mayhave the same general architecture as the instrument panel 10.

A section of the outer skin 14 acts as an integral airbag door 20,behind which is an airbag assembly 22 including a chute 24. The integralairbag door 20 hinges or pivots about upper and lower flexure linesadjacent generally horizontally elongated substrate edges 26 when anexpanding airbag bursts tear seams 28 in the outer skin 14. As such, thetear seams 28 are frangible. A “seamless” or hidden style of the outerskin 14 is preferred, whereby the frangible tear seams 28 are on thebackside surface thereof and are not visible to the vehicle occupant oruser. The tear seams 28 preferably have an H-shape, although otherconfigurations such as U-shapes and X-shapes can be employed.

The tear seams 28 can be created, for example, using a gantry-drivenlaser or an articulated robotically-driven knife, which horizontallyslides along the backside surface of the outer skin 14 after it isformed in order to partially sever or score the outer skin 14. Afterscoring, the tear seam 28 material remaining is greater than or equal toabout 0.3 mm to less than or equal to about 0.66 mm, with an average ofabout 0.50 mm. Although a thinner tear seam is available, the score linewill read through to the surface of the part if it is less than about0.457 mm. Therefore, a depth of the scoring is more than half but lessthan all of the skin thickness. When exposed to heat at about 120° C.for about 1000 hours, the score line on the skin does not exhibit anyheal back or rejoining. In other words, the TPO material of the currenttechnology does not exhibit self-healing of the frangible tear seams 28and helps to maintain the score line in a partially severed andseparated wall fashion. Moreover, because the integral airbag door 20having the frangible tear seams 28 comprises the TPO material, no skinfragmentation occurs from an airbag deployment at temperatures of about−30° C., about 23° C., about 80° C., or at about 120° C.Notwithstanding, all of the components described with reference to FIGS.1 and 2 can be casted, thermoformed, or slush molded from the TPOcomposition.

The TPO composition, whether TPO pellets or particles of a TPO powder,includes an OBC at a concentration of greater than or equal to about 50wt. % to less than or equal to about 70 wt. % and polypropylenecopolymer at a concentration of greater than or equal to about 10 wt. %to less than or equal to about 50 wt. % or greater than or equal toabout 10 wt. % to less than or equal to about 20 wt. %, wherein the wt.% is based on the total weight of the particles. Unless describedotherwise, it is understood that the “TPO composition” can be either theTPO pellets or TPO powder particles.

The OBC includes ethylene-1-octene copolymer having greater than orequal to about 50 wt. % to less than or equal to about 70 wt. % ethylenebased on the total weight of the ethylene-1-octene copolymer. Theethylene-1-octene copolymer has a density of greater than or equal toabout 0.887 g/cm³ to less than or equal to about 0.95 g/cm³ and a meltflow rate, as measured according to ASTM D-1238 (at 180° C. and 2.18kg), of greater than or equal to about 5 g/10 min to less than or equalto about 20 g/10 min.

The polypropylene copolymer is highly crystalline with a low impactstrength of greater than or equal to about 30 J/m to less than or equalto about 40 J/m, e.g., 35 J/m, and a high melt flow rate, as measuredaccording to ASTM D-1238 (at 230° C. and 2.16 kg), of greater than orequal to about 75 g/10 min to less than or equal to about 125 g/10 min,such as an exemplary melt flow rate of about 100 g/10 min.

The TPO composition can also include an adhesion promoter, which mayalso be referred to as a compatibilizer, at a concentration of greaterthan or equal to about 1 wt. % to less than or equal to about 10 wt. %.The adhesion promoter is a maleic anhydride-grafted OBC, wherein the OBCcan be the same OBC as what is combined with the polypropylenecopolymer, as discussed above. For example, the powder can includeethylene-1-octene copolymer as the OBC and maleic anhydride-graftedethylene-1-octene copolymer as the adhesion promoter. In some aspects,the adhesion promoter includes the maleic anhydride-graftedethylene-1-octene copolymer at a concentration of greater than or equalto about 95 wt. % to less than or equal to about 98 wt. %, maleicanhydride at a concentration of greater than or equal to about 1 wt. %to less than or equal to about 3 wt. %, and N-ethylethylenediamine at aconcentration of greater than or equal to about 1 wt. % to less than orequal to about 2 wt. %, wherein the wt. % is based on the total weightof the adhesion promoter.

The TPO composition can also include a stabilizer additive at aconcentration of greater than or equal to about 0.1 wt. % to less thanor equal to about 0.8 wt. %. The stabilizer additive can include sulfuror it can be substantially free or free of sulfur. By “substantiallyfree of sulfur,” it is meant that sulfur is not intentionally includedin the stabilizer additive, but may be present as an impurity at aconcentration of less than or equal to about 5 wt. % based on the totalweight of the stabilizer additive. Non-limiting examples of thestabilizer additive include 2,2,6, 6-tetram ethylpiperidin-4-yl-hexadecanoate, 2,2, 6,6-tetramethylpiperidin-4-yl-octadecanoate, and a combination thereof.

An adjunct composition component can also be included in the TPOcomposition at a concentration of greater than or equal to about 2 wt. %to less than or equal to about 6 wt. %. The adjunct composition includesat least a light stabilizer, at least one color pigment, or acombination thereof. The light stabilizer can be a visible lightstabilizer and/or an ultraviolet (UV) light stabilizer and may be anon-migratory hindered amine light stabilizer (HALS). The lightstabilizer and the at least one color pigment are provided in theadjunct composition at a concentration of greater than or equal to about0.3 wt. % to less than or equal to about 3 wt. %.

The TPO composition can yet further include a density modifier at aconcentration of greater than or equal to about 3 wt. % to less than orequal to about 10 wt. %. The density modifier can be a hydrous magnesiumsilicate mineral, such as talc, as a non-limiting example. The densitymodifier increases, and thus improves, the bulk density of the TPOpowder. In certain aspects, the bulk density of the TPO powder isgreater than or equal to about 18 lb/ft³ to less than or equal to about21 lb/ft³.

The TPO composition can additionally include a scuff and mar resistanceadditive. The scuff and mar resistance additive improves the TPOcomposition's ability to resist scuffing, marring, and scratching. Scuffand mar resistance additives include amides, lubricants (includingsilicon oils), organic-modified siloxanes, and grafted polymers, asnon-limiting examples. An exemplary and non-limiting scuff and marresistance additive is NOF®-ALLOY KA832 scratch improver (NOFCorporation).

The particles of the TPO powder have substantially uniform shapes (e.g.,substantially spherical) and sizes, the size of the particles beinggreater than or equal to about 50 μm to less than or equal to about 500μm or greater or than or equal to about 100 μm to less than or equal toabout 200 μm. Moreover, the particles have a narrow size distribution,in that greater than or equal to about 75%, greater than or equal toabout 80% or greater than or equal to about 90% of the particles have a+/−size deviation of less than or equal to about 30 μm, less than orequal to about 20 μm, less than or equal to about 15 μm, or less than orequal to about 10 μm. The TPO powder is also characterized by an angleof repose of greater than or equal to about 26° to less than or equal toabout 34°.

With reference to FIG. 3, the TPO composition is configured to be slushmolded (i.e., slush and rotary molded from the TPO powder), film casted,or thermoformed into an article 42, as discussed above. Thus, thearticle 42 comprises a TPO material 44 having a TPO matrix. As usedherein, a “TPO matrix” is a bulk TPO polymer-based composition formedfrom the TPO composition. Depending on a predetermined application, theTPO material 44 can be flexible and soft, such as a synthetic leather orother flexible soft skin, or relatively rigid. The hardness, rigidness,and flexibility of the TPO material 44 is provided by the TPO matrix.Accordingly, the article 42 comprising the TPO material 44 comprises thecomponents of the TPO, i.e., the OBC, the polypropylene copolymer, andthe optional adhesion promoter, stabilizer additive, adjunctcomposition, and/or density modifier.

In some aspects, and as shown in FIG. 3, the article 42 comprising theTPO material 44 is a flexible soft skin. The flexible soft skin can bedisposed over and about an open cell foam 46, such as a polyurethanefoam, which is disposed between a rigid substrate 48 and the TPOmaterial 44. Although an adhesive can be applied between the open cellfoam 46 and the flexible soft skin, the TPO material 44 directly bondsto the open cell foam 46 with an adhesion peel strength of greater thanor equal to about 3 N/in. As such, in some additional aspects, noadhesive is present to adhere the flexible soft skin to the open cellfoam 46. When the flexible soft skin is subjected to heat aging at about120° C. for about 500 hours, the flexible soft skin exhibits anelongation that does not change by more than about 30%, a tensilestrength that does not change by more than about 30%, and, when theflexible skin has a frangible tear seam, a tear strength that does notchange by more than about 30%.

In certain aspects, the TPO composition can additionally include anantimicrobial agent, such that a TPO material formed from the TPOcomposition is an antimicrobial TPO material. As used herein, the term“antimicrobial” provides that the antimicrobial TPO composition hasantiviral properties, such that an antimicrobial TPO material formedfrom the antimicrobial TPO composition is an antiviral material, and insome aspects, also has antibacterial properties, i.e., the antimicrobialTPO material can be an antiviral and antibacterial TPO material, and/orantifungal properties, i.e., the antimicrobial TPO material can be anantiviral and antibacterial and/or antifungal TPO material. As such,when a virus contacts the antimicrobial TPO material, the virus isdisabled, inactivated, destroyed, or “killed,” such that the virus is nolonger capable of infecting a subject. Similarly, when the antimicrobialTPO material has antibacterial properties, when a bacterium contacts theantimicrobial TPO material, the bacterium is killed. The term“antiviral” provides that the antiviral material disables, inactivates,destroys, or “kills” at least SARS-CoV-2, and in some aspects, alsokills other viruses, including other coronaviruses. The antimicrobialTPO material has antiviral activity due to its ability, for example, todisrupt virus host cell recognition by denaturing protein structures onviral surfaces, leading to the inactivation of viruses irrespective ofthe presence of a viral envelope. The antimicrobial TPO materialdisables, inactivates, destroys, or “kills” greater than or equal toabout 90%, greater than or equal to about 95%, greater than or equal toabout 98%, or greater than or equal to about 99%, such as about 90%,about 91° A, about 92%, about 93%, about 94%, about 95%, about 96%,about 97%, about 98%, about 99%, or about 99.9%, of SARS-CoV-2 viralparticles or plaque forming units (PFUs) in less than or equal to about4 hours, less than or equal to about 3 hours, less than or equal toabout 2 hours, less than or equal to about 1 hours, less than or equalto about 45 minutes, less than or equal to about 30 minutes, or lessthan or equal to about 15 minutes.

Accordingly, with reference to FIG. 4, the current technology providesan antimicrobial TPO material 50 formed from the antimicrobial TPOcomposition. The antimicrobial TPO material 50 is the same as the TPOmaterial 44 of FIG. 3, but further includes an antimicrobial agent. Theantimicrobial TPO material 50 includes a TPO matrix 52 and grapheneparticles 54 disposed and/or embedded in the TPO matrix 52, including atan exposed surface 55. Accordingly, the TPO matrix 52 comprises a curedTPO polymer that embeds antimicrobial particles, such as the grapheneparticles 54. Depending on a predetermined application, theantimicrobial TPO material 50 can be flexible and soft or relativelyrigid. The hardness, rigidness, and flexibility of the antimicrobial TPOmaterial 50 is provided by the TPO matrix 52.

The graphene particles 54 are antimicrobial particles or flakesincluding graphene or a graphene derivative, such as graphene oxide, asa non-limiting example, that provide at least the antiviral activity.The graphene particles 54 have greater than or equal to 1 to less thanor equal to 10 layers or greater than or equal to 6 to less than orequal to 10 layers, wherein each layer includes carbon atoms arranged ina two-dimensional honeycomb-shaped lattice. In various aspects, thegraphene particles 54 have 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 of thelayers. The graphene particles 54 have a diameter of greater than orequal to about 750 nm to less than or equal to about 250 μm, greaterthan or equal to about 1 μm to less than or equal to about 100 μm, orgreater than or equal to about 1 μm to less than or equal to about 50μm.

Without being bound by theory, the antimicrobial properties of grapheneand graphene-derivatives (e.g., graphene oxide) may be attributed to themovement of their electrons towards microbes. This migration causescytoplasmic efflux, decreases metabolism, affects lipid membrane,induces oxidative stress, produces reactive oxygen species (ROS), leadsto loss of glutathione, and causes microbial death. As non-limitingexamples, graphene can be used to kill different coronaviruses,including SARS-CoV strains.

In some aspects, the antimicrobial TPO material 50 includes anadditional antimicrobial agent. FIGS. 5 and 6 show antimicrobial TPOmaterials 50 a, 50 b including the TPO matrix 52 and the grapheneparticles 54. The antimicrobial TPO materials 50 a, 50 b of FIGS. 5 and6 further include metal oxide particles 56, wherein the metal oxideparticles 56 also provide at least antiviral activity, as defined abovein regard to the graphene particles 54. The metal oxide particles 56include cuprous oxide (Cu₂O) particles, zinc oxide (ZnO) particles,silver oxide (Ag₂O), or combinations thereof. These metal oxideparticles 56 release antimicrobial ions, such as Cu¹⁺, Ag¹⁺, and/orZn²⁺, and are used to prepare antimicrobial surfaces. Graphene and/orgraphene oxide can promote antimicrobial activities of these ionsfurther and improve the effectiveness. The metal oxide particles 56 havea diameter of greater than or equal to about 100 nm to less than orequal to about 100 μm, greater than or equal to about 200 nm to lessthan or equal to about 10 μm, greater than or equal to about 250 nm toless than or equal to about 5 μm, or greater than or equal to about 250nm to less than or equal to about 1.8 μm.

As shown in FIG. 5, the graphene particles 54 and the metal oxideparticles 56 are individually uniformly dispersed throughout the TPOmatrix 52 in the antimicrobial TPO material 50 a. By “individuallyuniformly dispersed,” it is meant that the graphene particles 54 and themetal oxide particles 56 are blended within the TPO matrix 52 withoutrespect to each other. Inasmuch as some of the graphene particles 54 andthe metal oxide particles 56 may be in contact with each other, thecontact is random and an artifact of a mixing step of a method offabricating the antimicrobial TPO material 50 a, as discussed below.Therefore, contact between a portion of the graphene particles 54 and aportion of the metal oxide particles 56 is not intended, but may bepresent.

As shown in FIG. 6, the graphene particles 54 and the metal oxideparticles 56 are present as graphene-metal oxide particle complexes 54,56 that are uniformly dispersed throughout the TPO matrix 52 in theantimicrobial TPO material 50 b. As such, the graphene particles 54carry the metal oxide particles 56 in the graphene-metal oxide particlecomplexes 54, 56. Nonetheless, it is understood that there may be some,i.e., a minority portion, of the graphene particles 54 and/or the metaloxide particles 56 that are present in the TPO matrix 52 individually,and not in a graphene-metal oxide particle complex 54, 56. As discussedbelow, the graphene-metal oxide particle complexes 54, 56 are formedprior to blending with the polymer that defines the TPO matrix 52 duringa fabrication process.

In all of the descriptions of the current technology provided herein,the antimicrobial TPO material 50 can alternatively be either theantimicrobial TPO material 50 a of FIG. 5 or the antimicrobial TPOmaterial 50 b of FIG. 6, unless otherwise stated.

The antimicrobial TPO material 50 of FIG. 4 includes the TPO matrix 52having polymeric components, i.e., the OBC, the polypropylene copolymer,and the adhesion promoter (when present), at a concentration of greaterthan or equal to about 50 wt. % to less than or equal to about 99 wt. %.The graphene particles 54 have a concentration in the antimicrobial TPOmaterial 50 of greater than or equal to about 0.05 wt. % to less than orequal to about 10 wt. %, greater than or equal to about 0.1 wt. % toless than or equal to about 5 wt. %, or greater than or equal to about0.25 wt. % to less than or equal to about 1 wt. %, including atconcentrations of about 0.05 wt. %, about 0.1 wt. %, about 0.15 wt. %,about 0.2 wt. %, about 0.25 wt. %, about 0.3 wt. %, about 0.35 wt. %,about 0.4 wt. %, about 0.45 wt. %, about 0.5 wt. %, about 0.55 wt. %,about 0.6 wt. %, about 0.65 wt. %, about 0.7 wt. %, about 0.75 wt. %,about 0.8 wt. %, about 0.85 wt. %, about 0.9 wt. %, about 0.95 wt. %,about 1 wt. %, about 1.5 wt. %, about 2 wt. %, about 2.5 wt. %, about 3wt. %, about 3.5 wt. %, about 4 wt. %, about 4.5 wt. %, about 5 wt. %,about 5.5 wt. %, about 6 wt. %, about 6.5 wt. %, about 7 wt. %, about7.5 wt. %, about 8 wt. %, about 8.5 wt. %, about 9 wt. %, about 9.5 wt.%, or about 10 wt. %. The TPO matrix 52 also includes the stabilizeradditive, adjunct composition, and/or density modifier when present withthe TPO composition.

The antimicrobial TPO materials 50 a, 50 b of FIGS. 5 and 6 have thesame composition as the antimicrobial TPO material 50, but furthercomprise greater than 0 wt. % to less than or equal to about 20 wt. % ofthe metal oxide particles 56. When the metal oxide particles 56 includemore than one type of metal oxide, such as at least one of Cu₂O or ZnO,the Cu₂O or ZnO are present at concentrations of greater than or equalto 0 wt. % to less than or equal to about 20 wt. % of the metal oxideparticles 56, individually, with the proviso that at least one of theCu₂O particles or the ZnO particles are present in the antimicrobial TPOmaterials 50 a, 50 b. Therefore, the antimicrobial TPO materials 50 a,50 b include greater than 0 wt. % to less than or equal to about 20 wt.% of at least one of the Cu₂O particles or the ZnO particles. The wt. %is based on the total weight of the antimicrobial TPO materials 50 a, 50b.

With reference to FIG. 7, in some aspects the antimicrobial TPO material50 is disposed over, about, and directly on a first sublayer orsubstrate 58. The first sublayer or substrate 58 can be a compressiblefoam, especially when the antimicrobial TPO material 50 is soft andflexible, or a rigid substrate, especially when the antimicrobial TPOmaterial 50 is rigid. Moreover, the first sublayer or substrate 58 canbe disposed on a second sublayer or substrate 60. For example, invarious aspects, the antimicrobial TPO material 50 is a soft flexiblematerial, such as a synthetic leather, that is disposed over acompressible foam first sublayer or substrate 58, which itself isdisposed on a rigid second sublayer or substrate 60.

The antimicrobial TPO materials 50, 50 a, 50 b described herein mayinclude at least the components described herein. However, it isunderstood that the antimicrobial TPO materials 50, 50 a, 50 b mayalternatively be limited to the components described herein or to aportion of the components described herein. For example, theantimicrobial TPO material 50 can include an antimicrobial agentcomprising, consisting essentially of, or consisting of graphene. By“consisting essentially of,” it is meant that the antimicrobial TPOmaterial 50 only intentionally includes graphene as the antimicrobialagent and is substantially free of any other antimicrobial agents. By“substantially free,” it is meant that additional antimicrobial agentsmay be included in trace amounts, i.e., less than or equal to about 5wt. % or less than or equal to about 1 wt. %, as impurities, wherein thetrace amounts do not affect the antimicrobial activity provided by thegraphene. Similarly, the antimicrobial TPO materials 50 a, 50 b caninclude antimicrobial agents comprising, consisting essentially of, orconsisting of graphene and at least one of Cu₂O, ZnO, or Ag₂O.

With reference to FIG. 8, the current technology also provides a method100 of making the TPO composition, including TPO pellets and TPO powder,the TPO powder being slush-molding grade. The TPO pellets have adiameter of greater than or equal to about 1 mm to less than or equal toabout 10 mm or greater than or equal to about 1 mm to less than or equalto about 6 mm. At block 102, the method 100 includes combining andmixing together the OBC, polypropylene, and optional adhesion promoter,stabilizer additive, adjunct composition, density modifier, and/orantimicrobial agent to form a mixture. Then, in block 104, the method100 includes melt compounding and extruding the mixture to form anextruded material. The melt compounding and extruding is performed, forexample, with a twin-screw extruder. The extruded material can be asolid, unitary thread or it can have a hollow interior, such as acylinder or pipe. Optional components can be added to the mixture duringthe melt compounding and extruding. The optional components include thedensity modifier (for modifying and improving the resulting TPOcomposition's bulk density), the stabilizer, the pigment (or colorant),the scuff and mar resistance additive (e.g., 20 g/10 min of NOF®-ALLOYKA832 scratch improver), or combinations thereof. The stabilizer andpigment can be provided in a single adjunct composition, as discussedabove.

Next, in block 106, the method 100 includes pelletizing the extrudedmaterial to form TPO pellets. The pelletizing is performed by cutting orgrinding the extruded material into the TPO pellets.

As shown in block 107, the method 100 includes processing the TPOpellets to form artificial leather or rolled films. The processingincludes cast film processing or calendaring. For example, the TPOpellets can be fed into a calendaring/cast film extruder to obtainrolled films. The artificial leather or rolled films are processable bycutting and sewing and/or by thermoforming.

In block 108, the method includes grinding the TPO pellets to form theTPO powder. The grinding can include, for example, hydrogrinding,pulverizing under water, to achieve a desired particle shape and sizedistribution, such that the particles pass through a sieve havingopenings that are less than or equal to about 500 μm. A density modifiercan be added to the TPO powder to modify and improve the TPO powder'sbulk density.

With reference to FIG. 9, the current technology also provides a method110 of fabricating an article from the TPO powder. At block 112, themethod 110 includes introducing the TPO powder to an interior of a mold,wherein the mold has an interior surface having a predetermined shape.Next, in block 114, the method 110 includes heating the mold to at leastpartially melt the TPO powder. In block 116, the method 110 includes,during the heating, rotating the mold to coat the interior surface withthe at least partially melted TPO powder. As shown in block 118, themethod 110 then includes cooling the mold to form the molded articlehaving the predetermined shape.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

What is claimed is:
 1. A thermoplastic polyolefin (TPO) compositioncomprising: an olefin-block copolymer (OBC) at a concentration ofgreater than or equal to about 50 wt. % to less than or equal to about70 wt. %; polypropylene copolymer at a concentration of greater than orequal to about 10 wt. % to less than or equal to about 20 wt. %; anadhesion promoter at a concentration of greater than or equal to about 1wt. % to less than or equal to about 10 wt. %; a sulfur-free stabilizeradditive at a concentration of greater than or equal to about 0.1 wt. %to less than or equal to about 0.8 wt. %; a composition comprisingnon-migratory hindered amine light stabilizers (HALS) and a colorpigment at a concentration of greater than or equal to about 2 wt. % toless than or equal to about 6 wt. %; and talc at a concentration ofgreater than or equal to about 3 wt. % to less than or equal to about 10wt. %.
 2. The TPO composition according to claim 1, wherein the OBCcomprises ethylene-1-octene copolymer comprising greater than or equalto about 50 wt. % to less than or equal to about 70 wt. % ethylene basedon the total weight of the ethylene-1-octene copolymer and having adensity of greater than or equal to about 0.887 g/cm³ to less than orequal to about 0.95 g/cm³.
 3. The TPO composition according to claim 2,wherein the ethylene-1-octene copolymer has a melt flow rate of greaterthan or equal to about 5 g/10 min to less than or equal to about 20 g/10min as measured according to ASTM D-1238 using 2.18 kg of theethylene-1-octene copolymer and a temperature of about 180° C.
 4. TheTPO composition according to claim 1, wherein the polypropylenecopolymer is crystalline, has a low impact strength of greater than orequal to about 30 J/m to less than or equal to about 40 J/m, and has amelt flow rate of about 100 g/10 min as measured according to ASTMD-1238 using 2.16 kg of the polypropylene copolymer and a temperature ofabout 230° C.
 5. The TPO composition according to claim 1, wherein theadhesion promoter comprises a maleic anhydride-grafted OBC.
 6. The TPOcomposition according to claim 1, wherein the adhesion promotercomprises: maleic anhydride-grafted ethylene-1-octene copolymer at aconcentration of greater than or equal to about 95 wt. % to less than orequal to about 98 wt. %; maleic anhydride at a concentration of greaterthan or equal to about 1 wt. % to less than or equal to about 3 wt. %;and N-ethylethylenediamine at a concentration of greater than or equalto about 1 wt. % to less than or equal to about 2 wt. %, wherein the wt.% is based on the total weight of the adhesion promoter.
 7. The TPOcomposition according to claim 1, wherein the sulfur-free stabilizeradditive comprises 2,2,6,6-tetramethylpiperidin-4-yl-hexadecanoate and2,2,6,6-tetramethylpiperidin-4-yloctadecanoate.
 8. The TPO compositionaccording to claim 1, wherein the TPO composition is in the form of aTPO powder comprising particles having a particle size of greater thanor equal to about 100 μm to less than or equal to about 200 μm.
 9. TheTPO composition according to claim 8, wherein the TPO powder has anangle of repose of greater than or equal to about 26° to less than orequal to about 34°.
 10. The TPO composition according to claim 8,wherein the TPO powder has a bulk density of greater than or equal toabout 18 lb/ft³ to less than or equal to about 21 lb/ft³.
 11. The TPOcomposition according to claim 1, wherein the TPO composition is in theform of TPO pellets.
 12. The TPO composition according to claim 1,further comprising graphene at a concentration of greater than or equalto about 0.05 wt. % to less than or equal to about 10 wt. % based on thetotal weight of the TPO composition.
 13. The TPO composition accordingto claim 12, further comprising a metal oxide, the metal oxidecomprising at least one of cuprous oxide (Cu₂O) or zinc oxide (ZnO) at aconcentration of greater than 0 wt. % to less than or equal to about 20wt. % based on the total weight of the particles.
 14. The TPOcomposition according to claim 1, wherein the TPO composition is part ofa slush and rotary-molded article.
 15. The TPO composition according toclaim 14, wherein the slush and rotary-molded article is an interiorcomponent of an automotive vehicle.
 16. The TPO composition according toclaim 14, wherein the slush and rotary-molded article is an automotivevehicle component, the automotive vehicle component being at least oneof an instrument panel, an A-pillar, a B-pillar, a C-pillar, a steeringwheel skin, an airbag cover, a door trim panel, a door handle, a pillarhandle, a roof handle, a center console, a knee bolster, a seatmechanism cover, or a sun visor.
 17. An article comprising athermoplastic polyolefin (TPO) material, the TPO material comprising: anolefin-block copolymer (OBC) at a concentration of greater than or equalto about 50 wt. % to less than or equal to about 70 wt. %; andpolypropylene copolymer at a concentration of greater than or equal toabout 10 wt. % to less than or equal to about 20 wt. %, wherein the wt.% is based on the total weight of the TPO material.
 18. The articleaccording to claim 17, wherein the TPO material further comprises: anadhesion promoter at a concentration of greater than or equal to about 1wt. % to less than or equal to about 10 wt. %; a sulfur-free stabilizeradditive at a concentration of greater than or equal to about 0.1 wt. %to less than or equal to about 0.8 wt. %; a composition comprisingnon-migratory hindered amine light stabilizers (HALS) and a colorpigment at a concentration of greater than or equal to about 2 wt. % toless than or equal to about 6 wt. %; and talc at a concentration ofgreater than or equal to about 3 wt. % to less than or equal to about 10wt. %, wherein the wt. % is based on the total weight of the TPOmaterial.
 19. The article according to claim 17, wherein the TPOmaterial further comprises graphene at a concentration of greater thanor equal to about 0.05 wt. % to less than or equal to about 10 wt. %based on the total weight of the TPO material.
 20. The article accordingto claim 19, wherein the TPO material further comprises a metal oxide,the metal oxide comprising at least one of cuprous oxide (Cu₂O) or zincoxide (ZnO) at a concentration of greater than 0 wt. % to less than orequal to about 20 wt. % based on the total weight of the TPO material.21. The article according to claim 17, wherein the TPO material is aflexible soft skin.
 22. The article according to claim 21, wherein thearticle further comprises a rigid substrate and an open cell foamdisposed between the rigid substrate and the TPO material.
 23. Thearticle according to claim 22, wherein the TPO material directly bondsto the open cell foam with an adhesion peel strength of greater than orequal to about 3 N/in.
 24. The article according to claim 23, whereinthe open cell foam comprises a polyurethane.
 25. The article accordingto claim 21, wherein the article is an airbag door comprising afrangible tear seam, and wherein no skin fragmentation occurs from anairbag deployment at −30° C., 23° C., 80° C., or 120° C.
 26. The articleaccording to claim 25, wherein the frangible tear seam is partiallysevered on a back surface of the flexible soft skin and the flexiblesoft skin does not exhibit self-healing of the partially-severedfrangible tear seam.
 27. The article according to claim 21, whereinafter heat aging at about 120° C. for about 500 hours, the flexible softskin exhibits: an elongation that does not change by more than about30%, a tensile strength that does not change by more than about 30%, andwhen the flexible soft skin has a frangible tear seam, a tear strengththat does not change by more than about 30%.
 28. The article accordingto claim 21, wherein the article is an interior trim panel of anautomotive vehicle.
 29. The article according to claim 28, wherein theinterior trim panel is an instrument panel, a pillar, a console, anarmrest, a door panel, a steering wheel, a knee bolster, a seat, or asun visor.
 30. A method of making a thermoplastic polyolefin (TPO)composition, the method comprising: mixing together an olefin-blockcopolymer (OBC), polypropylene, and an adhesion promoter to form amixture; melt extruding the mixture to form an extruded material; andpelletizing the extruded material to form TPO pellets.
 31. The methodaccording to claim 30, wherein the adhesion promoter comprises a maleicanhydride-grafted OBC.
 32. The method according to claim 31, wherein theadhesion promoter comprises maleic anhydride-grafted ethylene-1-octenecopolymer.
 33. The method according to claim 30, wherein the OBCcomprises ethylene-1-octene copolymer.
 34. The method according to claim30, further comprising: adding a density modifier to the powder forimproving the powder's bulk density.
 35. The method according to claim30, further comprising: adding at least one of a stabilizer, a colorant,a scuff and mar resistance additive, or a density modifier to themixture during the melt extruding.
 36. The method according to claim 30,further comprising: grinding the TPO pellets to form a TPO powder. 37.The method according to claim 36, wherein the grinding is performed inwater.
 38. The method according to claim 36, wherein the TPO powder isslush-molding grade.